Electrically operated fluid pump



Jan. 5, 1954 P. DUFFING 2,654,826

ELECTRICAL-LY OPERATED FLUID PUMP Filed May 14, 1952 2 Sheets-Sheet l Jan. 5, 1954 P. DUFFlNG ELECTRICALLY OPERATED FLUID PUMP 2 Sheets-Sheet 2 Filed May 14, 1952 .rlrdzllllll bg Inventor".

Patented Jan. 5, 1954 ELECTRICALLY OPERATED FLUID PUMP Paul Dufling, Berlin-Siemensstadt, Germany, assignor to Siemens-Schuckertwerke Aktiengesellschaft, BerlinSiemensstadt, Germany, a

German corporation Application May 14, 1952, Serial No. 287,671 Claims priority, application Germany June '7, 1951 11 Claims.

My invention relates to electrically-operated pumps, such as oil pumps, and has for its general object to provide a pump of a particularly simple and space-saving design especially as regards the electric pump drive means.

A more specific object of my invention is to devise an electrically driven pump of the Variablevolume chamber type in which the electric drive motor is so simplified and to such an extent integrated with the hydraulically active portion of the pump that it forms also the main structure of the variable-volume chamber.

Another object of my invention is to provide an electric pump, especially suitable for circulating liquid in electrical apparatus and machines, whose delivery varies automatically in dependence upon the electric current energizing the pump drive so that the pump output increases with an increase in current.

According to my invention, the pump comprises a slitted hollow cylinder of magnetizable material, such as iron or a ferromagnetic alloy, which is excited to contracting oscillations by means of an alternating magnet field that extends through the cylinder and is closed through the slit or slits.

When the field is produced by current of the customary line frequency (50 or 60 C. P. 8.), the

magnetic force in the slit alternates at twice that frequency (100 or 120 C. P. S.). The cylinder then oscillates in the same rhythm and accordingly contracts and expands the slit. The periodic variation in cylinder periphery causes a corresponding variation in cylinder volume. During each reduction in volume due to an increase in magnetic field strength, the fluid is forced out of the cylinder, for instance, through the slit. During each following increase in cylinder volume due to reduction in field strength, the fluid is inducted into the cylinder. Hence by providing suitable check-valve means, the oscillating cylinder is made to operate as a pump. The cylinder is preferably so dimensioned that its natural frequency is higher than double the frequency of the exciting alternating current.

According to another more specific feature of my invention, the cylinder slit is covered by a lid which provides check valve action and permits a flow of fluid substantially only from within the cylinder through the slit. Another check valve is preferably provided at a suction inlet of the cylinder chamber to permit at that place a flow substantially only in the inward direction.

According to another feature of my invention, the magnetic field for the cylinder is produced by means of an electric conductor that passes axially through the cylinder. This conductor may be given a hollow design so that it serves also as an inlet conduit for the pump. The communication between the hollow of the conductor and the interior of the cylinder is then controlled by the above-mentioned check valve means.

According to another feature of my invention, the expulsion of liquid from the interior of the pump cylinder is controlled by spring-biased covers which close the two axial ends of the cylinder and thus operate as check valves. It is then not necessary to also use the slit of the cylinder as an exit for the oil or other liquid.

If it is desired to secure a highly uniform fiow or" liquid, the induction space and the spac surrounding the cylinder are preferably provided with air chambers. In pumps whose centrally located conductor has a bore to form a conduit for the liquid to be pumped, this bore, according to another feature of my invention, is also designed as an equalizin air chamber. To this end, the bore is extended upwardly beyond the point where it communicates through a lateral opening with the interior of the cylinder. Air chambers in the space surrounding the pump cylinder may be formed by means of skirt members comparable to a divers bell. Instead, however, air-filled bodies of highly elastic material, such as oilresistant rubber, may be placed into the pump space adjacent to the cylinder.

The foregoing and more specific features of my invention are embodied in the example illustrated in the drawing, in which:

Fig. 1 shows an axial section through a pump according to the invention in conjunction with a fluid-circulating conduit system;

Fig. 2 shows a partial axial view of the pump proper;

Fig. 3 shows a similar axial view of a modified pump; and

Figs; 4 and 5 show respective sectional axial views of two other modifications.

The pump illustrated in Fig. 1 has a variablevolume chamber formed substantially by a hollow cylinder 1 which is slitted parallel to its axis. The slit 2 is covered by a lid 3 of flexible material. The lid is fastened to the outside of the cylinder I along one side of the slit so that it forms a check valve which opens the slit when the interior of the cylinder is under pressure and which closes the slit when the pressure outside of the cylinder.

is preponderant.

The cylinder I is centrally traversed by a rodshaped conductor 4 with an axial bore 5. The bore '5 communicates with the interior of the cylinder I through lateral port openings 15 covered by respective check valves 6. The valves 6 are located at the outside of the conductor od 4 and biased to closed position by a spring I6- which interconnects the two valve discs. The upper and lower axial sides of the cylinder 1 are closed by annular light-weight covers oi which is slidable on the rodA and biased to closed position by a spring 8. The pump-cylinder I is surrounded by a housing 9,. also of hollow cylin drical shape. The housing 9 has several skirtlike projections l peripherally along its interior surface. These projections form annular air chambers much in the manner or a divers bell. The housing 9 has its two axial sides covered by respective cap structures [1, each having a number of openings ll. The bore of rod 4 is extended upwardly beyond theport openings so that, it forms also an air chamber at: tit. The rod 4- with the cylinder t and the housing 9 is: disposed within a vessel: to which is surrounded by another. vessel 12.. The two vessels ltand t2 communicate with-each other ata placea'bove-the illustration. Electric current is suppiled to the rod 4 by means of a lead. [3.- insulatedfrom the vessels l2- and 14 at l9: and .28 respectively. The upper end (not illustrated) oi.- the rode is also connected to a terminal orlead for. the electric current. V When an alternating current passesthroughthe conductor rod 4', it produces a ma netic alternating field inthemagnetizable pumpcylinum: I. which alternatelycont-racts and expandsthe s1i't,. thus varying the volume enclosed by the cylinder. The variation in volume has a frequency twicetha't'ot the energizing. current. Dur ing. contracting intervals of the. cylinder, the litiu'idli's forced through the check-valve covers 1' into the housing 9' from which it reaches the; interior of. the vessell [4? and fiows as. indicated by arrows,-through.adesiredcirculatory pathd-nto theispaoe'between vessels IA'andi I3.- D-uring ex pansion of the cylinder;v the liquid is inducted from the vessel IZ 'throughbQre 5'..p0rts l5 and check valves 6 into .theint'eriorof the pump cylin oer 1. Consequently, acontinuous circulation oftheliquid" ismai'ntained by; the pump V As mentioned, the? slit of the cylinder may be covered by a lid" 3i to operate asalcheck. valve. However, the pump may? als'ollie designedi'so that the liquid. isejected" from the cylinder only through the op'enin'gs -of one or two valve covers I. In that case; adiaplira'gm' member covering the slit 2 is tightly secured alongboth' sides-of the". slit 'a'si'is shown; for instance, for eachofTthe flexible diaphragms? 3 5" ertaining to the modi fication illustratediiTFig'. '3'.

The pump cylinder" mayal s'o be" equippedwith a plurality of longitudinal slits, the individual parts of the cylinderbeing then interconnected by. resilient diaphragm connections aLsoas' shown Fig; 3'? The: cylinder and" connecting. diaphragm members are preferahly so dimensioned that the. natural frequency. of the entire cylinderand diaphragmassemblyiishigher than twice the frequency or-the alternating current I Instea'd of providingthe pump Housing Q 'With' skirt members lflf'f the "housing" may b'e'ig'iven' a substantially-straight inner surface; and the' aii" chambers-fiesired' forbetteruniformityofthenow ofliquid'may tlien' beprovidedby plapirrgjhollow elastic and air filled bodies into" the housing:

Such a design is preferable in cases where it is desired to prevent the liquid from being charged with air. Another modification securing the same result consists in making the housing 9 of rubber or similar resilient material, and giving it a double wall? so that the air enclosed between the two walls acts as an air chamber.

Embodiments of the kind just-mentioned are shown in Figs. 4 and 5 wherein the same referencenumerals are used as in Fig. 1 for corresponding respective elements. According to Fig. 4, the outer housing 9 of the pump is straight cylindrical. The lower axial side of the pump cylinder is covered by a lid 2| which serves as an abutment for one or several hollow air-filled bodies 22 of rubber or the like material placed intothe lower cap 23.

In the embodiment of Fig. 5, the outer housing 2 1' of' the pump consists of a double-walled structure of rubber or similarly elastic material whose hollow 2'5 filled-with air. The end caps 26 overlap; the structure 2s sufficiently to hold-it in place whilepermitting it tosomewhat expand during the compressioninterval'. In all other respects the embodiments of Figs. 4 and'5 are designe'd'and operative as described above with reference to Figs. 1 and 21 While pum s according to my invention are-a plic'able for general purposes, they are especially advantageous in" cases' where space is at a pre miuin and where" alternating current for operat in'g" thepump is readily available. For instance,- a favorable application of suclr pumps is' in co'm nectionwith-- circuit breakers" and other electric producing; conductor of the pump may formpart of'the electric conductor means that supply the current-to'the electric apparatus, as is the'caseinfg' fieima' slitted'hollow cylinder of magnetiz'af- 61ematerial surrounding said conductor in said field to'xbe" periodically contracted due to said fieldj two annular cover members sun-"cunning said conductor" and having" residectiv'e" spring-s biasing-said cover memb ers againstsaid cylinder at: opposite: axial sides riespeetiveiy,. and inlet valve means c'o-znmunieating with the-interior of saidfeylinder.

2:- An electric 1 pump, comprising an alternat ing ourrent conductor for providing: an alternat inggfield; a slitte'cl hollow cylinder-of magnetizable material surrounding said conductor in said field to be periodically contracted due to I said field,- sa-id conduc-tor havingh longitudinal bore; and

having a lateral port-joining. saidborewith the interior of saidcylinder;- saidbore having a closed endspaee axially-beyond said port-to form an airchamben-d-iquid conduit means includillgaSEti-dbQTB-fi-Ild said port aswell as said cylinder interior and-having inlet valve means at said port, andoutlet valvemeans communicatiiigi with the interior or sa'idcylindr.

3. Anemoneomp;- coinprisingan' alternat ing-current conductor having a magnetic field, a hollow cylinder of magnetizable material having a longitudinal slit and being disposed around said conductor to be periodically contracted due to said field, a movable lid member covering said slit at the outside of said cylinder to form a check valve opposed to inward flow of liquid, cover means closing said cylinder at opposite axial sides respectively and comprising a cover member and a spring resiliently holding said cover member against said cylinder to form another check valve opposed to inward flow of liquid, said conductor having a longitudinal hollow and having a lateral port opening joining said hollow with the interior of said cylinder, and check valve means disposed at said port opening and opposed to outward flow of liquid from said cylinder.

4. An electric pump, comprising alternatingcurrent means having a magnetic field when in operation, a slitted hollow cylinder of magnetizable material forming a variable-volume chamber and being positioned adjacent to said means to be periodically contracted by said field, and check valve means communicating with said chamber and forming a fluid path together therewith.

5. An electric pump, comprising an alternating-current conductor for providing an alternating field, a slitted hollow cylinder of magnetizable material forming a variable-volume chamber and surrounding said conductor to be periodically contracted due to said field, and check valve means communicating with said chamber and forming a fluid path together therewith.

6. An electric pump, comprising alternatingcurrent means having a magnetic field, a hollow cylinder of magnetizable material having a longitudinal slit and forming a variable-volume chamber, said cylinder being disposed adjacent to said means to be periodically contracted by said field, a movable lid member covering said slit to form an outlet valve, and inlet valve means connected with said chamber.

'7. An electric pump, comprising an alternating-current conductor for providing an alternating field, a slitted hollow cylinder of magnetizable material surrounding said conductor in said field to be periodically contracted due to said field, said conductor having a tubular portion and having a bore through which the interior of said tubular portion communicates with the interior of said cylinder so as to form a liquid flow path through said tubular portion and said bore and said cylinder, an inlet valve means at said bore to permit liquid flow sub- 6 stantially only in the direction from said tubular portion to said cylinder interior, and outlet valve means communicating with said interior of said cylinder.

8. An electric pump, comprising alternatingcurrent means having a magnetic field, a slitted hollow cylinder of magnetizable material disposed adjacent to said means to be periodically contracted due to said field, said cylinder having respective axial openings, cover means closing said openings and comprising a cover member and a spring resiliently holding said cover member against said cylinder to form an outlet valve, and inlet valve means communicating with the interior of said cylinder.

9. An electric pump, comprising alternatingcurrent conductor means having a magnetic field, a slitted hollow cylinder of magnetizable material surrounding said conductor means to be periodically contracted due to said field, said conductor means and said cylinder having a substantially vertical axis, a housing structure for liquid having a wall concentrically surrounding said cylinder in spaced relation thereto, said structure having annular skirt means extending from said wall inwardly and downwardly so as to form air pockets around said cylinder, and liquid conduit means forming a fiuid path through said cylinder and having check valve means in said path.

10. An electric pump, comprising alternatingcurrent means having a magnetic field, a slitted hollow cylinder of magnetizable material surrounding said means and being disposed in said field to be periodically contracted thereby, said cylinder having a natural frequency higher than twice the frequency of said alternating-current means, and inlet valve means and outlet valve means hydraulically joined with said cylinder.

11. An electric pump, comprising alternatingcurrent means having a magnetic field, a slitted hollow cylinder of magnetizable material disposed in said field to be periodically contracted due to said field, a housing structure for liquid having a wall concentrically surrounding said cylinder in spaced relation thereto, a hollow gasfilled and elastically compressible body disposed within said housing structure, and check valve means communicating with the interior of said cylinder and forming a unidirectional fluid-flow path together therewith with said cylinder and with said housing structure.

PAUL DUFFING.

No references cited. 

